On Wed, Feb 05, 2020 at 10:30:50AM -0800, Christoph Hellwig wrote: > > + /* > > + * There are no users as of now. Once users are there, fix dm code > > + * to be able to split a long range across targets. > > + */ > > This comment confused me. I think this wants to say something like: > > /* > * There are now callers that want to zero across a page boundary as of > * now. Once there are users this check can be removed after the > * device mapper code has been updated to split ranges across targets. > */ Yes, that's what I wanted to say but I missed one line. Thanks. Will fix it. > > > +static int pmem_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff, > > + unsigned int offset, size_t len) > > +{ > > + int rc = 0; > > + phys_addr_t phys_pos = pgoff * PAGE_SIZE + offset; > > Any reason not to pass a phys_addr_t in the calling convention for the > method and maybe also for dax_zero_page_range itself? I don't have any reason not to pass phys_addr_t. If that sounds better, will make changes. > > > + sector_start = ALIGN(phys_pos, 512)/512; > > + sector_end = ALIGN_DOWN(phys_pos + bytes, 512)/512; > > Missing whitespaces. Also this could use DIV_ROUND_UP and > DIV_ROUND_DOWN. Will do. > > > + if (sector_end > sector_start) > > + nr_sectors = sector_end - sector_start; > > + > > + if (nr_sectors && > > + unlikely(is_bad_pmem(&pmem->bb, sector_start, > > + nr_sectors * 512))) > > + bad_pmem = true; > > How could nr_sectors be zero? If somebody specified a range across two sectors but none of the sector is completely written. Then nr_sectors will be zero. In fact this check shoudl probably be nr_sectors > 0 as writes with-in a sector will lead to nr_sector being -1. Am I missing something. > > > + write_pmem(pmem_addr, page, 0, bytes); > > + if (unlikely(bad_pmem)) { > > + /* > > + * Pass block aligned offset and length. That seems > > + * to work as of now. Other finer grained alignment > > + * cases can be addressed later if need be. > > + */ > > + rc = pmem_clear_poison(pmem, ALIGN(pmem_off, 512), > > + nr_sectors * 512); > > + write_pmem(pmem_addr, page, 0, bytes); > > + } > > This code largerly duplicates the write side of pmem_do_bvec. I > think it might make sense to split pmem_do_bvec into a read and a write > side as a prep patch, and then reuse the write side here. Ok, I will look into it. How about just add a helper function for write side and use that function both here and in pmem_do_bvec(). > > > +int generic_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff, > > + unsigned int offset, size_t len); > > This should probably go into a separare are of the header and have > comment about being a section for generic helpers for drivers. ok, will do. Thanks Vivek -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel